EP3469625A1 - Thermocompression bonding with raised feature - Google Patents
Thermocompression bonding with raised featureInfo
- Publication number
- EP3469625A1 EP3469625A1 EP16904801.4A EP16904801A EP3469625A1 EP 3469625 A1 EP3469625 A1 EP 3469625A1 EP 16904801 A EP16904801 A EP 16904801A EP 3469625 A1 EP3469625 A1 EP 3469625A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- substrate
- raised feature
- metal layer
- layer
- bond
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000758 substrate Substances 0.000 claims abstract description 110
- 238000000034 method Methods 0.000 claims abstract description 32
- 239000010931 gold Substances 0.000 claims abstract description 23
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052737 gold Inorganic materials 0.000 claims abstract description 20
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 17
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000010703 silicon Substances 0.000 claims abstract description 16
- 238000003825 pressing Methods 0.000 claims abstract description 4
- 229910052751 metal Inorganic materials 0.000 claims description 58
- 239000002184 metal Substances 0.000 claims description 58
- 239000010949 copper Substances 0.000 claims description 12
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 7
- 238000004026 adhesive bonding Methods 0.000 claims description 7
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 7
- 239000004065 semiconductor Substances 0.000 claims description 5
- 238000000059 patterning Methods 0.000 claims description 4
- 239000000919 ceramic Substances 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 3
- 238000005530 etching Methods 0.000 claims description 2
- 230000008569 process Effects 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- QUCZBHXJAUTYHE-UHFFFAOYSA-N gold Chemical compound [Au].[Au] QUCZBHXJAUTYHE-UHFFFAOYSA-N 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00261—Processes for packaging MEMS devices
- B81C1/00269—Bonding of solid lids or wafers to the substrate
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/02—Containers; Seals
- H01L23/10—Containers; Seals characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C2203/00—Forming microstructural systems
- B81C2203/01—Packaging MEMS
- B81C2203/0172—Seals
- B81C2203/019—Seals characterised by the material or arrangement of seals between parts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C2203/00—Forming microstructural systems
- B81C2203/03—Bonding two components
- B81C2203/033—Thermal bonding
- B81C2203/037—Thermal bonding techniques not provided for in B81C2203/035 - B81C2203/036
Definitions
- This invention relates to a methodology for bonding together two microfabrication substrates.
- Microelectromechanical systems are devices which are manufactured using lithographic fabrication processes originally developed for producing
- MEMS devices may be made in quantity and in very small sizes. MEMS techniques have been used to manufacture a wide variety of transducers and actuators, such as accelerometers and electrostatic cantilevers.
- MEMS devices are often movable, they may be enclosed in a rigid structure, or device cavity formed between two substrates, so that their small, delicate structures are protected from shock, vibration, contamination or atmospheric conditions. Many such devices also require an evacuated environment for proper functioning, so that these device cavities may need to be hermetically sealed after evacuation. Thus, the device cavity may be formed between two substrates which are bonded using a hermetic adhesive.
- Thermocompression bonds are known for achieving a hermetic seal between two flat surfaces.
- Thermo-compression bonds can be strong when the bonding area is large.
- surface roughness will generally obviate a hermetic bond, due to the separation of the two bonding planes by surface asperities.
- a TCB can be hermetic if the bond area is small, because loading force during bonding can plastically deform the surface asperities to the point that the two bonding planes are no longer separated.
- the bond will be weak.
- the current invention uses a raised feature on one of the bonding surfaces to achieve a hermetic thermocompression bond.
- the high initial pressure of the raised feature on the opposing surface provides for a hermetic bond without fracture of the raised feature, while the complete embedding of the raised feature into the opposing surface allows for the two bonding planes to come into contact.
- This large contact area provides for high strength.
- a method may include providing a first and a second substrate, forming a first layer of a metal over the first substrate, providing a raised feature the second substrate; forming a second layer of a metal over the raised feature on the second substrate, pressing the first substrate against the second substrate to form a substrate pair, with a temperature, pressure and duration sufficient to achieve a thermocompression bond, and bonding the substrate pair with a thermocompression bond between the first metal layer and the second metal layer, around the raised feature, wherein adhesive bonding strength between the first substrate and the second substrate is in the vicinity of the raised feature as a result of thermocompression bond.
- the resulting device may comprise a bond between a first substrate and a second substrate, wherein the bond includes a first metal layer on the first substrate, a raised feature formed on the second substrate, and a second metal layer over the second substrate and the raised feature, wherein most adhesive bonding strength between the first substrate and the second substrate is in the vicinity of the raised feature as a result of thermocompression bonding between the first metal layer and the second metal layer.
- Fig. la is a schematic cross sectional diagram of the bonding layers and raised feature prior to bonding
- Fig. lb is a schematic cross sectional diagram of the bonding layers and raised feature after bonding
- Fig. 2 is a plan view of the bond, raised feature, and sealed device after bonding
- Figs. 3a-3f illustrate a process for forming the raised feature.
- thermocompression bond is characterized by atomic motion between two surfaces brought into close contact. The atoms migrate from one crystal lattice to the other one based on crystal lattice vibration. This atomic interaction adheres the surfaces. Thermocompression bonding using two layers of gold (Au) is known, but the technique has the deficiencies described above. Other materials may also be capable of
- thermocompression bonding including aluminum (Al) and copper (Cu) bonds.
- Al aluminum
- Cu copper
- the substrate and the raised feature are both silicon, and the first metal layer and the second metal layer are both gold, with a thickness of about 0.5 to 6 microns.
- the substrates may comprise at least one of glass, metal, semiconductor and ceramic.
- Fig. la shows two bonding surfaces 100, 110 before bonding.
- these surfaces are metal layers, composed of Au that is 0.5microns to
- One surface 110 also has a raised feature 150 formed therein.
- the raised feature 150 in the gold layer 110 may be a result of a conformal deposition of the gold material over a substrate 200 with a corresponding raised feature 250 formed thereon. As will be described below, adhesive bonding strength may exist near this raised feature 150 when applied against an opposing gold layer 100 on a second substrate 300.
- Fig. la is a first layer 100 of a first metal formed on a first substrate 300, a second layer 110 of a metal formed over a raised feature 250 on a second substrate 200.
- the conformal deposition of the second metal layer 110 may result in a corresponding raised feature 150 in the second metal layer.
- the device according to this process may include a bond between a first substrate and a second substrate, comprising a first metal layer on the first substrate, a raised feature on the second substrate; and a second metal layer over the second substrate and the raised feature, wherein adhesive bonding strength between the first substrate and the second substrate is in the vicinity of the raised feature as a result of
- thermocompression bonding between the first metal layer and the second metal layer may mean a region spanning about 10 diameters of the raised feature.
- the raised feature 250 in substrate 200 may be formed by the process described below with respect to Figs. 3a-3f.
- the width (or diameter) of the raised feature 250 may be about 5microns and its height of the raised feature above a plane of the substrate may be about lmicron.
- the radius of curvature of the raised feature 150 may be less than about 5 microns, and preferably less than about 3 microns.
- the raised feature may have a generally cylindrical, spherical or pyramidal shape, for example, pointed at the top on a broader base. The detailed shape of the raised feature may be a result of the technique used to create it.
- the raised feature 250 may be a continuous perimeter around a device, as shown in Fig.
- the plurality of raised features may be spaced close enough together such that the thermocompression bond is still achieved and the bond is still hermetic.
- the plurality of raised features may therefore form a series, spaced around and generally encircling, or around, a device.
- the width of the bonding planes may be between about 50microns and about 200microns. After bonding these surfaces may appear as shown in Fig. lb.
- the raised feature 150 is completely embedded in the material of the first metal layer, upper surface 100. More generally, when the first substrate is pressed against the second substrate to form a substrate pair, the raised feature is completely embedded in the first metal layer. Because the first substrate and the second substrate are flat, a contact area of the thermocompression bond may comprise at least about 75% of the width of the bondline. In some embodiments, the percentage of the bond line that is bonded is the width of the bondline minus the mis-alignment divided by the width.
- the width is 50um and the mis-alignment is 2um, resulting in percent bonded area of around 96%.
- Fig. 2 is a plan view of the bond, the device cavity and the enclosed device.
- This bond line 210 and raised feature 250 may form a substantially hermetic seal ring around a die or device 220.
- the width of the first metal layer and the second metal layer may be about 50 microns to about 200 microns, which may define a width of a bondline of the same dimension, about 50 microns to about 200 microns.
- the first metal layer and the second metal layer may both comprise at least one of gold, aluminum and copper of a thickness between about 0.5 microns and 6 microns..
- a microfabricated device 220 such as a MEMS or an integrated circuit (IC) may be formed on either the first or the second substrate.
- the raised feature 250 may form a continuous perimeter around the device 220.
- the raised feature 250 is formed in the surface of substrate 200, and comprises the material of the substrate 200.
- Figs. 3a-3f illustrate the process to form the raised feature in this embodiment.
- a silicon substrate 200 Fig. 3a
- a pad oxide layer 205 of 300 - 1000A thickness may be grown as a stress relief layer (Fig. 3b).
- a low pressure chemical vapor deposition a low pressure chemical vapor deposition
- LPCVD LPCVD deposits a layer 215 of S1 3 N 4 , followed by a patterning process to prevent the local oxidation of the underlying Si, as shown in Fig. 3d.
- the width of this patterned feature will determine the radius of curvature of the raised feature.
- a thick thermal oxide 225 is grown as shown in Fig. 3e.
- the thickness of this oxide layer is roughly twice that of the required raised feature height.
- the thermal oxide is chemically etched away, leaving the raised features 250.
- the following procedure may be used: First form a first oxide layer over the substrate surface, then deposit a layer of hard mask over first oxide layer, pattern the hard mask and the first oxide layer; and form a second oxide layer over the substrate; and finally remove the second oxide layer to leave the raised feature in the substrate.
- the second oxide layer may be about twice a thickness of the hard mask layer.
- the method for forming the raised feature may include forming a layer of silicon nitride on a silicon wafer, patterning the layer of silicon nitride; growing a thick thermal oxide on the silicon substrate; and etching the thermal oxide away, to leave the raised feature.
- the thickness of the thermal oxide may be about twice the thickness of the silicon nitride layer.
- the method may include providing a first and a second substrate, providing a raised feature the first substrate; forming a first layer of a metal over the raised feature on the first substrate, pressing the first substrate against the second substrate to form a substrate pair, with a temperature, pressure and duration sufficient to achieve a thermocompression bond, and bonding the substrate pair with a thermocompression bond between the first metal layer and the second metal layer, around the raised feature, wherein most adhesive bonding strength between the first substrate and the second substrate is in the vicinity of the raised feature as a result of thermocompression bond.
- the method may also be applied to other types of substrates in addition to silicon.
- a glass, metal, semiconductor or ceramic substrate may be used on which a raised feature of another mechanically competent material is deposited.
- Silicon nitride for example, may be formed on a semiconductor substrate using chemical vapor deposition (CVD).
- CVD chemical vapor deposition
- the gold layers 100 and 110 may then deposited conformally over this raised feature, and the process proceeds as previously described.
- a first gold layer described above may be deposited on a first silicon substrate 100, and a second gold layer may be formed over the second substrate 200 with raised feature 250.
- the substrates may then be pressed together with a heat and pressure sufficient to achieve the gold-gold thermocompression bond.
- a bonding temperature may be between 200 and 450 °C with an applied force above 40 kN for 20 to 45 min may generally be sufficient to achieve the bond.
- the pressure may be about 40 kN and the duration may be about 45 minutes, and the temperature may be about 200 to about 450 centigrade. More generally, and for other materials such as aluminum (Al) or copper (Cu), the first substrate may be pressed against the second substrate with a pressure of about 20 to 80 kN for at least about 20 minutes, at a temperature of between about 200 centigrade and 450 centigrade, and wherein the first metal layer and the second metal layer both comprise at least one of gold, aluminum and copper.
- Al aluminum
- Cu copper
- the raised feature Under the loading pressure applied during bonding, the raised feature is completely embedded in the opposing surface, as was shown in Fig. la and lb. This brings the two bonding planes into contact.
- the high initial pressure of the raised feature on the opposing surface provides for a hermetic bond without fracture of the raised feature
- the complete embedding of the raised feature into the opposing surface allows for the two bonding surfaces to come into contact. This large contact area provides for high strength as shown in Fig. lb.
- the bonding temperature can be from 400 to 450 °C with an applied force above 70 kN for 20 to 45 minutes.
- a bonding temperature of around 380 to 450 °C with an applied force between 20 to 80 kN for 20 to 60 min may be sufficient.
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Power Engineering (AREA)
- Micromachines (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
Abstract
Description
Claims
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2016/036593 WO2017213652A1 (en) | 2016-06-09 | 2016-06-09 | Thermocompression bonding with raised feature |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3469625A1 true EP3469625A1 (en) | 2019-04-17 |
EP3469625A4 EP3469625A4 (en) | 2020-03-04 |
Family
ID=60578853
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16904801.4A Withdrawn EP3469625A4 (en) | 2016-06-09 | 2016-06-09 | Thermocompression bonding with raised feature |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP3469625A4 (en) |
JP (1) | JP6755558B2 (en) |
WO (1) | WO2017213652A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113336182B (en) * | 2021-05-19 | 2023-05-26 | 中山大学南昌研究院 | Micro-electromechanical system packaging structure and preparation method thereof |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000263533A (en) * | 1999-03-16 | 2000-09-26 | Sumitomo Metal Electronics Devices Inc | Ceramic base and its manufacture |
US7569926B2 (en) * | 2005-08-26 | 2009-08-04 | Innovative Micro Technology | Wafer level hermetic bond using metal alloy with raised feature |
US8809097B1 (en) * | 2010-09-22 | 2014-08-19 | Crystal Solar Incorporated | Passivated emitter rear locally patterned epitaxial solar cell |
US9028628B2 (en) * | 2013-03-14 | 2015-05-12 | International Business Machines Corporation | Wafer-to-wafer oxide fusion bonding |
US9305890B2 (en) * | 2014-01-15 | 2016-04-05 | Taiwan Semiconductor Manufacturing Company, Ltd. | Package having substrate with embedded metal trace overlapped by landing pad |
-
2016
- 2016-06-09 EP EP16904801.4A patent/EP3469625A4/en not_active Withdrawn
- 2016-06-09 WO PCT/US2016/036593 patent/WO2017213652A1/en unknown
- 2016-06-09 JP JP2018560114A patent/JP6755558B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
EP3469625A4 (en) | 2020-03-04 |
JP6755558B2 (en) | 2020-09-16 |
WO2017213652A1 (en) | 2017-12-14 |
JP2019523983A (en) | 2019-08-29 |
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A4 | Supplementary search report drawn up and despatched |
Effective date: 20200131 |
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